As golf balls having high spin performance at approach shot and long flight distance, two-layer structured core type or two-layer structured cover type golf balls, which comprise a center formed from soft rubber, an intermediate layer formed on the center and from rubber or resin that is relatively harder than the center and a cover formed from soft material, have been proposed (Japanese Patent No. 2910516, Japanese Patent Publication Nos. 239068/1997, 151226/1998, 151320/1999 and the like).
In Japanese Patent No. 2910516, a multi-piece golf ball, of which the center has a diameter of not less than 29 mm, the intermediate layer has a JIS-C hardness of not less than 85, and the specific gravity of the center is larger than that of the intermediate layer, is described. However, since ionomer resin is used for the intermediate layer as a main component, the rebound characteristics of the resulting golf ball are poor, and the flight distance when hit by a driver is not sufficiently obtained.
In Japanese Patent Kokai Publication No. 239068/1997, a three-piece solid golf ball which comprises a core, an intermediate layer and a cover is described. The core has a JIS-C center hardness of not more than 75 and a JIS-C surface hardness of not more than 85, the surface hardness of the core is higher than the center hardness of the core by 8 to 20, the hardness of the intermediate layer is higher than the surface hardness of the core by not less than 5, and the hardness of the cover is lower than that of the intermediate layer by not less than 5, and the dimples occupy at least 62% of the ball surface. However, since the hardness difference between the center hardness and the surface hardness of the center is small and ionomer resin is used for the intermediate layer, the shot feel is hard and poor. In addition, the spin amount at the time of hitting is large, and the flight distance when hit by a driver is not sufficiently obtained.
In Japanese Patent Publication No. 151226/1998, a multi-piece golf ball, of which the center has a distortion of at least 2.5 mm under a load of 100 kg, the Shore D hardness of the intermediate layer is at least 13 degrees higher than that of the cover, and the ball as a whole has an inertia moment of at least 83 g-cm2, is described. However, since ionomer resin is used for the intermediate layer, the shot feel is hard and poor. In addition, the rebound characteristics are poor, and the flight distance when hit by a driver is not sufficiently obtained.
In Japanese Patent Publication No. 151320/1999, a multi-piece golf ball, of which the center and intermediate layer are formed from rubber composition comprising polybutadiene rubber as a main component, the center has a diameter of 15 to 22 mm and a Shore D hardness of 40 to 70, is described. However, the diameter of the center is too small, and the rebound characteristics of the resulting golf ball are poor. In addition, the spin amount at the time of hitting is large, and the flight distance when hit by a driver is not sufficiently obtained.
There has been no golf ball, which is superior in flight distance, shot feel and scuff resistance.